It's not like we'd be able to tell you for sure by looking at a picture anyway...

The sparkles are probably little pieces of mica, or quartz, or some other crystal. Probably harmless. But the real test is to drop a few drops of hydrochloric acid on one of the rocks and see if it foams or fizzes. If it does, don't put it in your aquarium.

That appears to be a nice rockyard! Here in Florida, the ones I have close to me are filled with limestone-containing rocks that have no business in any aquariums other than alkaline African Cichlid tanks. Looks like the ones at your local rockyard are more granite-based, which is a good thing.